6-Methoxy indoline acetate and its 5-nitro and 5-amino derivatives

ABSTRACT

Novel antibacterially-active compound, 1,2,8,8a-cyclopropa[c]benzo[1,2-b:-4,3-b&#39;]dipyrol-4(5H)-one, prepared by a novel chemical process. This compound, as well as antibacterially-active intermediates, can be used to eradicate or control susceptible bacteria, for example, B. subtilis, K. pneumonia, S. lutea, S. aureus, and M. avium. 
     Claimed compounds include those of the formula ##STR1## wherein R 1 , R 2 , R 3  and R 4  are as defined hereinafter.

This is a division of application Ser. No. 207,838, filed Nov. 18, 1980, now abandoned.

BACKGROUND OF THE INVENTION

Antibiotic CC-1065, is disclosed and claimed by its chemical and physical parameters in U.S. Pat. No. 4,169,888. Subsequently, the structure of antibiotic CC-1065 was elucidated as disclosed in "Structure Proof of Antibiotic CC-1065", D. G. Martin, C. G. Chidester, D. J. Duchamp, and S. A. Mizsak, J. Antibiot., 33 902 (1980). The structure of antibiotic CC-1065 is shown in CHART 1. Antibiotic CC-1065 consists of a 3-fragment system with the most labile portion of the molecule being the fragment named 1,2,8,8a-cyclopropa[c]benzo[1,2-b:4,3-b']dipyrol-4(5H)-one, which is denoted herein as compound(12). Attempts to obtain this fragment by degradation of antibiotic CC-1065 have failed. Thus, there is no known prior art method to obtain compound(12).

BRIEF SUMMARY OF THE INVENTION

Compound(12) of the subject invention can be made by an 11-step process disclosed in CHART 2. This compound, as well as certain intermediates disclosed herein, are active against certain bacteria, for example, Bacillus subtilis, Klebsiella pneumonia, Sarcina lutea, Staphylococcus aureus, and Mycobacterium avium. Accordingly, these compounds can be used to disinfect washed and stacked food utensils contaminated with S. aureus. Further, the antibacterially-active compounds of this invention can be used as a bacteriostatic rinses for laundered clothes, and for impregnating papers and fabrics; and, they are also useful for suppressing the growth of sensitive organisms in plate assays and microbiological media. In general, the antibacterially-active compounds of this invention can be used in the same manner as disclosed for antibiotic CC-1065 in U.S. Pat. No. 4,169,888. These uses are well-known in the antibiotic art. Accordingly, bacteriological techniques are readily available to persons skilled in this art to practice such uses.

DETAILED DESCRIPTION OF THE INVENTION

As disclosed above, the 11-step process for preparing compound(12) is shown in Chart 2. These steps are as follows:

Step 1--The first step (aromatic nucleophilic substitution) in the synthetic approach is described by J. Bourdais and C. Mahieu, Compt. Redux [C], 263, 84 (1966). Also see J. Bourdais and C. Germain, Tet. Letters, 195 (1970). The various R₁ groups can be introduced on the phenol precursor of (1) by procedures described in the literature (appropriate references detailed under step 8). The various malonates, β-keto esters, and β-diketones employed are all known compounds.

Step 2--Reduction. When R₂ =alkoxy, diisobutylaluminum hydride is the reagent of choice. Reaction conditions are quite specific (see Example 1) for optimum yields. When R₂ =alkyl or phenyl, standard reduction procedures employing sodium borohydride can be employed.

Step 3--Functional group interchange. The chemistry described specifically herein is in the case of X=OSO₂ CH₃. The mesylate or tosylate (for example) can be prepared under standard conditions known in the art employing pyridine (with or without solvent, such as methylene chloride) or other acid acceptors such as trialkylamines (with solvent) and the corresponding sulfonyl chloride. The halogen analogs of 4 can be prepared under standard procedures known in the art such as Ph₃ P/CCl₄ (CBr₄) and N-iodosuccinimide/triphenylphosphine.

Step 4--Reduction-cyclization. This step is a novel preparation of indolines (dihydroindoles). This involves the reduction of the nitro to the amino group with concomitant intramolecular cyclization to give (5). The reduction step described in detail herein utilizes H₂, PtO₂ in alcohol in the presence of a tertiary amine. These are standard hydrogenation conditions in the art. Palladium or nickel catalysts can also be employed and bases other than a tertiary amine, such as pyridine, can be utilized. Alternate reducing conditions can employ Fe or TiCl₃ in acid or SnCl₂. This may then require a separate step involving treatment with base to induce the cyclization to (5). An example of a reduction with iron is the use of Fe/CH₃ CO₂ H/CH₃ CH₂ OH (G. S. Ponticello and J. J. Baldwin, J. Org. Chem., 44, 4003 (1979). These conditions would be required if R₁ =CH₂ Ph or --CH₂ CH=CH₂.

The concept of nitro reduction followed by in situ cyclization to indoles is advanced by A. D. Batcho and W. Leimgruber, German Offen. 2057840 (1971), which is a significant improvement over the older Reissert procedure of reductive cyclization to indoles. (See R. J. Sundberg, The Chemistry of Indoles, pp. 176-183. Academic Press, N.Y., 1970).

Step 5--Substitution of labile group. This step is required due to the incompatibility of X with the chemistry of step 8. It involves the replacement of X with an acetate or the conjugate base of a C₁ -C₅ alkyl carboxylic acid under standard conditions (alkali carboxylate in acetone, DMF, or alcohol). Since some hydrolysis can occur when X=OSO₂ CH₃, the reaction mixture is treated with acetic anhydride prior to isolation of (6).

Step 6--Nitration can be performed under a variety of conditions described in the literature including nitric acid in acetic acid, acetic anhydride, sulfuric acid, acetic acid/H₂ O, alcohol, and nitroalkanes. The regioselectivity of this reaction is supported by the spectroscopic data obtained.

Step 7--Reduction of the nitro to the amino group follows the same chemical description given in step 4 with the omission of base.

Step 8--Indole synthesis. This procedure is based generally on the indole chemistry of Gassman [P. G. Gassman, et.al., J. Am. Chem. Soc., 96, 5494, 5508, 5512 (1974)]. Several modifications are required which are not disclosed or suggested in Gassman's work. The sequence of the chemical events and some of the intermediates are depicted in CHART 3. The α-thiomethyl esters are known.

This process deviates from the published Gassman route by employing the chlorosulfonium complex, A, and reacting it with the aniline, (6); Gassman prepares the chloroamine of an aniline and reacts it with the thioether in making oxindoles. Secondly, two different bases are employed in the process, whereas Gassman uses two equivalents of the aniline followed by a base₂. Although triethylamine, diisopropylethylamine, bis(1,8-dimethyl amino)naphthalene, and the like both work for base₁ and base₂, the preferred for base₁ is bis(1,8-dimethylamine)naphthalene, and triethylamine for base₂. Different solvents such as chloroform, acetonitrile, tetrahydrofuran (THF), and methylene chloride can be used, the latter is preferred. The temperature range is from -50° to -80° and the reaction is run under an inert atmosphere. The cyclization to the oxindole B is best promoted by acid catalysis as described by Gassman (2N HCl, ether and/or ethyl acetate).

The final reduction to (9) (reductive elimination) can be accomplished with lithium aluminum hydride (as described by Gassman) or diborane type reagents, the latter being far superior. The preferred reagent is (CH₃)₂ S.BH₃ in THF at room temperature for 24 hours.

Step 9--This deprotection step (removal of R₁) is described in detail for R₁ =CH₃ in Example 8. Although there are a number of procedures described in the art involving methyl ether cleavage, only alkyl mercaptide in hexamethylphosphorictriamide (HMPA) under an inert atmosphere (95°-110°) have been found to be effective [S. C. Welch and A.S.C.P. Rao, Tet. Letters, 505 (1977) and T. R. Kelly, H. M. Dali, and W-G. Tsang, Tet. Letters, 3859 (1977), or Me₂ S.BBr₃ in dichloroethane (P. G. Willard and C. B. Fryhle, Tet. Letters, 3731 (1980)].

When R₁ =CH₂ Ph, standard hydrogenolysis conditions suffice to deprotect (H₂, Pd/C) [Org. Reactions, 7, 263 (1953)]. When R₁ =CH₂ SCH₃, mercuric chloride in acetonitrile/H₂ O removes the ether (R. A. Holton and R. G. Davis, Tet. Letters, 533 (1977). When R₁ =CH₂ OCH₃, moderate acid will generate the phenol-10, such as acetic acid [J. Med. Chem., 9, 1 (1966) or Synthesis, 244 (1976)]. In fact, this protecting group may be lost in step 6, however, it can be reintroduced prior to step 7 under standard conditions. When R₁ =--CH₂ OCH₂ CH₂ OCH₃, the phenol can be generated by ZnBr₂ or TiCl₄ in CH₂ Cl₂ [Tet. Letters, 809 (1976)]. When R₁ =--CH₂ CH═CH₂, several two-step procedures will deprotect the ether (Pd/C in alcohol/ Ang. Chem. Int. Ed., 15, 558 (1976); SeO₂, CH₃ CO₂ H in dioxane/Tet. Letters, 2885 (1970); t-BuOK, DMSO followed by H₂ SO₄ in acetone/J. Chem. Soc., 1903 (1965); RhCl(PPh₃)₃, DABCO in alcohol followed by pH2 [J. Org. Chem., 38, 3224 (1973)]. When R₁ =--CH₂ CH₂ Si(R₂)₃ deprotection is effected by Bu₄ NF [H. Gerlach, et. al., Helv. Chim. Acta, 60, 3039 (1977)].

Step 10--See step 3.

Step 11--This step (when X=Br) is promoted by contact with silica gel as well as occurs on standing in protic solvents. This reaction will also proceed in the presence of such bases as tertiary amines, pyridine, t-butoxide, and the like and weak aqueous bases such as bicarbonate and carbonate.

The following examples are illustrative of the products and process of the invention, but are not to be construed as limiting. All percentages are by weight and all solvent mixture proportions are by volume unless otherwise noted.

EXAMPLE 1 Preparation of the 2-aryl-1,3-propandiol (3) from the aryldiethylmalonate (2)

To 400 ml of THF under N₂ cooled in an ice-water bath is added 100 g of DIBAL* (0.70 mole) in 400 ml of toluene. To this stirred solution is added 33.0 g (0.105 mole) of the arylmalonate (2) in 100 ml of THF. The rate of addition is controlled to keep the reaction temperature below 5°. After the addition is complete the ice bath is removed. The reaction is quenched after 3 hours total reaction time by the portion-wise addition of the solution to cold 3N HCl with stirring (approximately 1.5 l). The mixture is then extracted with 1 l of EtOAc followed by 1000 ml CH₂ Cl₂. The combined organic phases are dried over Na₂ SO₄ and concentrated to a red-brown residue (21.2 g). Chromatography of the residue on 500 g silica gel with 60% EtOAc/hexane→100% EtOAc gradient eluent affords 11.7 g (49% yield) of the diol (3) (U-62,598) as a light red oil (solidifies on standing in the freezer).

NMR (CDCl₃): 7.5-7.0 (m, 3H), 3.80 (s, 3H), 4.0-3.3 (m, 7H--includes 2 OH).

MS: Calc. for C₁₀ H₁₃ NO₅ : 227.0794. Found: 227.0780.

Analysis: Calc: C, 52.86, H, 5.76, N, 6.16. Found: C, 53.40, H, 5.77, N, 5.99.

EXAMPLE 2 Preparation of the 2-aryl-1,3-propandiol bismesylate (4) from the 2-aryl-1,3-propandiol (3)

To 4.7 g (0.2 moles) of the diol (3) in 100 ml of dry pyridine under N₂ at 0°-5° is added with stirring 6.8 g (0.06 mole) of methanesulfonyl chloride. After stirring at 5° for 30 minutes followed by room temperature for 90 minutes, the solution is concentrated in vacuo, then taken up in CH₂ Cl₂ /1N HCl. The organic phase is separated, dried over Na₂ SO₄, concentrated to a residue. Trituration with EtOAc affords an off-white solid and the mother liquors can be chromatographed on silica gel (EtOAc eluent) to afford a total yield of 6.65 g (86% yield), m.p. 122°-3° (recrystallized from acetone) of compound(4), bismesylate (U-62,597).

NMR (Acet-d₆): 7.7-7.2 (m, 3H), 4.62 (d, 4H, J=J Hz), 4.11 (t, 1H, J=7 Hz), 3.92 (s, 3H), 3.06 (s, 6H).

Analysis: Calc for C₁₂ H₁₇ NO₉ S₂ : Calc: C, 37.59, H, 4.47, N, 3.65. Found: C, 37.35, H, 4.44, N, 3.59.

This compound was assayed by a standard tube dilution assay against L1210 mouse leukemia cells in culture and gave the following results:

ID₉₀ (μg/ml)=6.0; ID₉₀ (μg/ml)=18.

EXAMPLE 3 Preparation of the 6-methoxyindoline bismesylate (5) from the 2-aryl-1,3-propandiol bismesylate (4)

To 1.91 g (0.005 mole) of compound(4) in 30 ml of THF, 20 ml of EtOAc, and 150 ml of absolute ethanol is added 1.5 ml of triethylamine and 400 mg of PtO₂. This solution is placed under 7-10 psi H₂ pressure with shaking for 30 minutes. The reaction solution is then filtrated over celite and concentrated in vacuo. After several CH₂ Cl₂ azeotropes in vacuo, the residue is ultimately taken up in 100 ml of CH₂ Cl₂ and cooled under N₂ in an ice bath. To the stirred solution is added 1.5 ml of triethylamine followed by the dropwise addition of 900 μl methane sulfonylchloride. After stirring for 30 minutes, the solution is allowed to come to room temperature for 60 minutes. The solution is then washed with 1N HCl, dried over Na₂ SO₄, and concentrated. The residue is rapidly chromatographed on 150 g silica gel with 500 ml of 60% EtOAc/hexane followed by 1000 ml of 80% elution; recovered 1.3 g (78% yield) of an off-white solid, m.p. 122°-3° (recrystallized from ethanol) of compound(5), the 6-methoxyindoline bismesylate (U-62,586).

NMR (DMF-d₇): 7.36 (d, 1H, J=8.5 Hz), 7.00 (d, 1H, J=2 Hz), 6.69 (dd, 1H, J=2, 8.5 Hz), 4.47 (2H, d, J=6 Hz), 4.3-3.6 (m, 3H), 3.80 (s, 3H), 3.20 (s, 3H), 3.07 (s, 3H).

Analysis: Calc for C₁₂ H₁₇ NS₂ O₆ : Calc: C, 42.97, H, 5.11, N, 4.18. Found: C, 42.87, H, 5.27, N, 4.29.

This compound was assayed by a standard tube dilution assay against L1210 mouse leukemia cells in culture and gave the following results:

ID₅₀ (μg/ml)=4.8; ID₉₀ (μg/ml)=10.

EXAMPLE 4 Preparation of the 6-methoxy indoline acetate (6) from the 6-methoxy indoline bismesylate (5)

To 13.0 g (39 mmol) of the 6-methoxy indoline bismesylate (5) in 30 ml of DMF is added 800 ml of abs. ethanol followed by 32 g of sodium acetate. This hereogeneous solution is refluxed under N₂ for 24 hours, cooled, and concentrated in vacuo. The residue is treated with 100 ml of acetic anhydride for 2 hours (stirring at room temperature), then concentrated in vacuo. The residue is taken up in CH₂ Cl₂ /H₂ O and the organic phase is separated, dried over Na₂ SO₄, filtered through charcoal, and concentrated to an oil which solidifies; 11.6 g of compound(6), the 6-methoxy indoline acetate (100%; if necessary, further purification is possible with silica gel chromatography employing 60% EtOAc/hexane eluent).

NMR (CDCl₃): 7.17 (d, 1H, J=8.5 Hz), 7.02 (d, 1H, J=2 Hz), 6.60 (dd, 1H, J=2, 8.5 Hz), 4.18 (d, 2H, J=6 Hz), 4.1-3.4 (m, 3H), 3.78 (s, 3H), 2.91 (s, 3H), 2.05 (s, 3H).

Analysis: Calc for C₁₃ H₁₇ NO₅ S: Calc: C, 52.16, H, 5.76, N, 4.68. Found: C, 52.13, H, 5.79, N, 5.27.

MS: Calc: 299.0827. Found: 299.0823.

EXAMPLE 5 Preparation of the 5-nitro-6-methoxy indoline acetate (7) from the 6-methoxy indoline acetate (6)

To 500 mg (1.67 mmole) of the 6-methoxy indoline acetate (6) in 20 ml of nitromethane is added 90 μl of 90% HNO₃. The cooled reaction solution (O°-5°) is stirred for 30 minutes, then warmed to room temperature for 30 minutes. The solution is diluted with CH₂ Cl₂ and aqueous sodium bicarbonate. The organic phase is separated, dried over Na₂ SO₄, and concentrated. The residue is chromatographed on 50 g silica gel (60% EtOAc/hexane eluent→100% EtOAc) yield; 440 mg (76% yield) of a yellow solid, m.p. 175°-7° (recrystallized from ethanol) of compound(7), the 5-nitro-6-methoxy indoline acetate (U-62,696).

NMR (DMF-d₇): 7.91 (s, 1H), 7.20 (s, 1H), 4.27 (d, 2H, J=6 Hz), 4.3-3.7 (m, 3H), 3.98 (s, 3H), 3.17 (s, 3H), 2.07 (s, 3H).

Analysis: Calc for C₁₃ H₁₆ N₂ O₇ S: Calc: C, 45.34, H, 4.68, N, 8.14. Found: C, 44.81, H, 4.77, N, 8.16.

This compound was assayed by a standard tube dilution assay against L1210 mouse leukemia cells in culture and gave the following results:

ID₅₀ (μg/ml)=>50; ID₉₀ (μg/ml)=>50.

EXAMPLE 6 Preparation of the 5-amino-6-methoxy indoline acetate (8) from the 5-nitro-6-methoxy indoline acetate (7)

To 4.5 g (13 mmole) of the 5-nitro-6-methoxy indoline acetate (7) in 50 ml of THF and 150 ml of absolute ethanol is added 500 mg PtO₂ and shaken under 10 psi of H₂ until uptake ceases (approximately 60 minutes). Filter and concentrate in vacuo. Upon concentration, 3.0 g of product precipitates out. This is filtered off and the mother liquors rapidly chromatographed on 100 g silica gel with EtOAc eluent to afford an additional 0.6 g. The total yield (3.6 g) is 88%; m.p. 134°-5° (from acetone/cyclohexane) of compound (8), the 5-amino-6-methoxy indoline acetate (U-62,697).

NMR (CDCl₃): 7.02 (s, 1H), 6.65 (s, 1H), 4.16 (d, 2H, J=6 Hz), 4.1-3.5 (m, 3H), 3.83 (s, 3H), 3.6 (br. s, 2H), 2.83 (s, 3H).

Analysis: Calc for C₁₃ H₁₈ N₂ O₅ S: Calc: C, 49.67, H, 5.77, N, 8.91. Found: C, 49.74, H, 5.72, H, 8.94.

This compound was assayed by a standard tube dilution assay against L1210 mouse leukemia cells in culture and gave the following results:

ID₅₀ (μg/ml)=>50; ID₉₀ (μg/ml)=>50.

EXAMPLE 7 Preparation of the 4,5-pyrrolo-6-methoxy indoline (9) from the 5-amino-6-methoxy indoline acetate (8)

To 14 ml of dry CH₂ Cl₂ under N₂ at -75° is added 6.0 ml of a Cl₂ /CH₂ Cl₂ solution (20 μl Cl₂ /ml CH₂ Cl₂). To this stirred solution is added 370 μl (2.5 mmole) of CH₃ (CH₃ S)CHCO₂ C₂ H₅ (prepared from CH₃ (Br)CHCO₂ C₂ H₅ and methyl mercaptide by the procedure of E. H. Wick, T. Yamanishi, H. C. Wertheimer, Y. E. Hoff, G. F. Proctor, and S. A. Goldblith, J. Agr. Food Chem., 9, 289 (1961)). After 5 minutes a solution of 470 mg (2.2 mmole) of 1,8-bisdimethylaminonaphthalene and 628 mg (2.0 mmole) of the anilinoidoline (8) in 3.0 ml of dry CH₂ Cl₂ is added dropwise over 15 minutes. The red solution is stirred for 2 hours at -75°, then 350 μl of triethylamine in 650 μl of CH₂ Cl₂ is added dropwise over several minutes. The cooling bath is removed. When the reaction solution reaches room temperature it is briefly concentrated in vacuo. To the residue is added 5 ml EtOAc, 25 ml of ether and 6 ml of 2N HCl and stirred vigorously for 2 hours. The organic phase is separated and the aqueous is extracted with 1:1 EtOAc/Et₂ O. The organics are combined, dried over Na₂ SO₄ and concentrated. At this point the residue is taken up in 10 ml of THF and treated with 3.0 ml of 2M BH₃.SMe₂ overnight at room temperature under N₂. Alternatively the diastereomeric oxindoles (B) derived from the acid treatment can be isolated at this point by silica gel chromatography (50 g; 60% EtOAc/hexane to 90% EtOAc/hexane).

GS-MS: m/e M⁺ 414 (15%), 227 (100%)-2' 1% SE-30

NMR(CDCl₃): 8.4(br. s, 1H), 7.11 (s, 1H), 4.5-3.7 (m, 5H), 3.90 (s, 3H), 2.95 (s, 3H), 2.10 (s, 3H), 1.92 (s, 3H), 1.82 (s, 3H)-major diasteromer (2.5/l); minor diastereomer shows the following differences-1.99 (s, 3H), 1.76 (s, 3H) for --SCH₃ and --CH₃, the NH is is at 7.7 and the CH₂ region is 4.3-3.6 ppm.

The aqueous phase from the acid treatment can be neutralized and extracted with CH₂ Cl₂. The CH₂ Cl₂ solution can be dried, concentrated, and chromatographed on silica gel with 50% acetone/cyclohexane to give 40% recovery of starting material (anilinoindoline) and 20% deacylated starting material.

The boranedimethylsulfide reductive elimination (on B) reaction is worked up by quenching with 1N HCl until gas evolution ceases and taking up in CH₂ Cl₂ /H₂ O. The separated organic phase is dried over Na₂ SO₄ and concentrated. The residue is chromatographed on silica gel (50% acetone/cyclohexane) to afford 155 mg of product (9); 25% isolated yield-85% based on recovered starting material), m.p. 182°-183° (phase change at 160°, recrystallized from chloroform), the 4,5-pyrrollo-6-methoxy indoline (9) (U-62,233).

NMR (CDCl₃): 8.3 (br. s, 1H), 6.96 (s, 2H), 4.2-3.5 (m, 5H+OH), 3.92 (s, 3H), 2.87 (s, 3H), 2.41 (s, 3H).

Analysis: Calc for C₁₄ H₁₈ N₂ O₄ S: Calc: C, 54.17, H, 5.84, N, 9.03. Found: C, 53.49, H, 5.96, N, 9.42.

GC-MS: of O-acetate-m/e M⁺ 352 (13%), 213 (100%)-2'-1% SE-30, temperature 150°-260° (10°/minute); single peak

This compound was assayed by a standard tube dilution assay against L1210 mouse leukemia cells in culture and gave the following results:

ID₅₀ (μg/ml)=>4; ID₉₀ (μg/ml)=>4.

EXAMPLE 8 Preparation of the 4,5-pyrrolo-6-hydroxy indoline (10) from the 4,5-pyrrolo-6-methoxy indoline (9)

To 10 ml of dry, degassed HMPA (hexamethylphosphorictriamide) under N₂ at room temperature is added 350 μl of butyl mercaptan. The solution is cooled in an ice-water bath and 2.0 ml of 1.5M n-BuLi in hexane is added dropwise. After allowing the reaction to come to room temperature 100 mg (0.3 mmole) of the indole (9) is added with stirring. The solution is heated to 100° for 2.5 hours. The reaction is followed by tlc (50% acetone/cyclohexane) and when conversion appears approximately 75% complete (by vanillin/phosphoric acid spray), heating is terminated. The cooled solution is poured into 1N HCl (100 ml) and extracted with 20 ml EtOAc. The separated organic phase is washed with additional 50 ml of water. The aqueous phases are combined and back-extracted with 20 ml of EtOAc. The organic phases are then combined, dried over Na₂ SO₄, concentrated in vacuo, and applied to a 100 g silica gel column and eluted with 50 % acetone/cyclohexane. Afforded are 25 mg of starting material and 45 mg of product (10) 44% isolated yield, 69% based on recovered S.M.), the 4,5-pyrrolo-6-hydroxy indoline (U-62,370).

NMR (Acet-d₆): 7.8 (br. s, 1H), 7.03 (s, 1H), 6.83 (s, 1H), 4.25-3.25 (m, 5H), 2.86 (s, 3H), 2.36 (s, 3H).

This product was treated with acetic anhydride (1.0 ml) and 20 mg of NaOAc overnight, then taken up in CH₂ Cl₂ /H₂ O. The organic phase was separated, dried over Na₂ SO₄, and concentrated.

NMR (CDCl₃): 7.8 (br. s, 1H), 7.16 (s, 1H), 6.97 (s, 1H), 4.42, 4.20 (dd, 2H), 4.2-3.7 (m, 3H), 2.86 (s, 3H), 2.40 (s, 3H), 2.35 (s, 3H), 2.06 (s, 3H).

GC-MS: m/e M⁺ 380 (25%), 199 (100%)-2'-1% SE-30

This compound was assayed by a standard tube dilution assay against L1210 mouse leukemia cells in culture and gave the following results:

ID₅₀ (μg/ml)=>5; ID₉₀ (μg/ml)=>5.

EXAMPLE 9 Preparation of the 4,5-pyrrolo-6-hydroxy indoline bromide (11) from the 4,5-pyrrolo-6-hydroxy indoline alcohol (10)

To 25 mg (65 μmole) of the substrate alcohol in 1.0 ml of dry acetonitrile under N₂ at room temperature is added 33 mg (100 μmole) of CBr₄ and 26 mg (100 μmole) of triphenyl phosphine (Ph₃ P). After stirring for 30 minutes an additional 11 mg CBr₄ and 8 mg of Ph₃ P are added. The reaction is taken up in CH₂ Cl₂ /H₂ O after 60 minutes (total). The organic phase is separated, dried over Na₂ SO₄, and concentrated. The residue is placed on three 20×20 cm 250μ silica gel plates and eluted with 50% acetone/cyclohexane. Approximately 8 mg of the higher R_(f) product (0.64; alcohol R_(f) =0.45) is recovered, compound (11), the 4,5-pyrrolo-6-hydroxy indoline bromide (U-62,694).

NMR (CDCl₃): 8.5 (br. s, 1H), 7.1 (s, 1H), 6.9 (s, 1H), 4.23 (d, 2H, J=6 Hz), 4.0-3.5 (m, 3H), 2.89 (s, 3H), 2.38 (s, 3H).

Beilstein test: positive

MS: Calc. for C₁₆ H₂₃ N₂ O₃ ⁷⁹ BrSSi=430.0382, Found 430.0375 (mono-TMS); m/e M⁺ 430/432 (14%), 271 (90%), 147 (100%).

This compound was assayed by a standard tube dilution assay against L1210 mouse leukemia cells in culture and gave the following results:

ID₅₀ (μg/ml)=0.12; ID₉₀ (μg/ml)=0.37.

EXAMPLE 10 Preparation of the 4,5-pyrrolo-6-hydroxy indoline mesylate (11) from the 4,5-pyrrolo-6-hydroxy indoline alcohol (10)

To 20 mg (65 μmole) of the alcohol substrate (10) in 1.0 ml pyridine in an ice bath with stirring under N₂ is added 8 μl of methanesulfonyl chloride (70 μmole). After 30 minutes an additional 2 μl of CH₃ SO₂ Cl is added and worked up with 2N HCl/CH₂ Cl₂ after 60 minutes total reaction time. The organic phase is separated, dried over Na₂ SO₄, and concentrated. Tlc indicates mostly lower R_(f) product (0.28 in 50% acetone/cyclohexane, alcohol R_(f) =0.46) and some higher R_(f) product (0.66). Preparative tlc (3-20×20 cm 250μ silica gel plates) affords 2 mg of higher R_(f) material (NMR indicated only one CH₃ SO₂ group; it is probably the chloride) and 9 mg of the lower R_(f) material, compound(11) (U-62,695).

NMR (Acet-d₆): 8.6 (br. s, 1H), 6.97 (s, 1H), 6.74 (s, 1H), 4.3 (m, 2H), 4.1-3.6 (m, 3H), 2.96 (s, 3H), 2.79 (s, 3H), 2.26 (s, 3H).

This compound was assayed by a standard tube dilution assay against L1210 mouse leukemia cells in culture and gave the following results:

ID₅₀ (μg/ml)=1.0; ID₉₀ (μg/ml)=3.3.

EXAMPLE 11 Preparation of 1,2,8,8a-cyclopropa[c]benzo[1,2-b:4,3-b']dipyrol-4(5H)-one (12), N-(methylsulfonyl)

In following the procedure to prepare the 4,5-pyrrolo-6-hydroxy indoline bromide (step 10), if the reaction mixture prior to work-up is concentrated in vacuo and applied to thick-layer silica gel plates directly, instead of isolating the higher R_(f) (0.64) product bromide, a new lower R_(f) band (0.32) is noted and recovered as compound(12).

NMR (CDCl₃): 9.5 (br. s, 1H), 6.83 (dd, H_(a)), 6.34 (s, H_(b)), 4.10 (d, H_(c)), 3.93 (dd, H_(d)), 3.04 (s, 3H), 2.93 (m, H_(e)), 2.00 (d, 3H), 1.97 (dd, H_(f)), 1.37 (dd, H_(g)).

    ______________________________________                                         J.sub.c,e = 0.0 Hz  J.sub.e,g = 4.4                                            J.sub.c,d = 9.7     J.sub.f,g = 4.4                                            J.sub.d,e = 4.7     J.sub.NH,a = 2.0                                           J.sub.e,f = 7.7     J.sub.a,CH.sbsb.3 = <1.0                                   ______________________________________                                    

MS: silylation with BSTFA (DMF containing 1% TMS-Cl) gave m/e M⁺ 386/388 (22, 12% corresponding to product +Me₃ SiCl)

UV: (methanol) λ224, 272, 338.

This compound was assayed by a standard tube dilution assay against L1210 mouse leukemia cells in culture and gave the following results:

ID₅₀ (μg/ml)=0.13; ID₉₀ (μg/ml)=0.42.

EXAMPLE 12 Alternate preparation of compound(12)

To the 4,5-pyrrolo-6-hydroxy indoline bromide (or mesylate) (0.1 mmole) in 1 ml of methylene chloride is added 0.1 mmole of diisopropylethyl amine and stirred under N₂ for 24 hours at room temperature. The reaction solution is taken up in 10 ml of methylene chloride, washed with 0.1N HCl, dried over Na₂ SO₄, and concentrated to give the desired product. Further purification can be accomplished by silica gel chromotography.

Compounds (11) and (12) exhibit antibacterial activity against B. subtilis, K. pneumonia, S. lutea, S. aureus and M. avium. ##STR2## 

I claim:
 1. A compound of the formulawherein R₁ is selected from the group consisting of CH₃ --, --CH₂ Ph, CH₂ ═CHCH₂ --, --CH₂ SCH₃, --CH₂ OCH₃, CH₂ OCH₂ CH₂ OCH₃, --CH₂ CCl₃, and --CH₂ CH₂ Si(R₂)₃ ; and R₂ and R₃ are H, alkyl of from 1 to 5 carbon atoms, inclusive, and phenyl; and R₄ is selected from the group consisting of SO₂ R₂, SO₂ CH₂ CO phenyl, CO₂ CH₂ Z, where Z is selected from the group consisting of CH₂ I, CCl₃, CH₂ SO₂ R₂, Ph (phenyl), and fluorenylmethyl.
 2. A compound of the formula ##STR3## wherein R₁, R₂, R₃ and R₄ are as defined in claim
 1. 3. A compound of the formula ##STR4## wherein R₁, R₂, R₃ and R₄ are as defined in claim
 1. 4. A compound, according to claim 1, having the formula ##STR5##
 5. A compound, according to claim 4, having the formula ##STR6##
 6. A compound, according to claim 3, having the formula ##STR7## 